Lock up your carbon? Defra study results
Defra has just published the data and conclusions from a study it funded on organic farming and minimum tillage effects on the carbon content of arable soils in England and Wales.
In summary, the ADAS team that carried out the work concludes that there is limited scope for additional soil carbon storage/accumulation from zero/reduced tillage practices and organic material applications, over and above present day normal farm practice. Indeed, there are questions over the implications of such practices for nitrous oxide (N2O) emissions and the overall balance of greenhouse gas emissions (expressed on a CO2-C equivalent basis).
They go on to assert that soil organic carbon (SOC) accumulation is finite and reversible, and SOC levels will only remain elevated if the practice is continued indefinitely. Only the application of biosolids (treated sewage sludge), compost and paper crumble appear to offer the same level of CO2-C ‘savings’ that have been predicted for land-use change options (e.g. reversion of arable land to permanent grassland, woodland or willow/poplar biomass production).